1. Field of the Invention
The invention relates to an LED driving circuit and a control circuit.
2. Description of Related Art
At present, the electric energy accounts for 14% of the global energy each year, which is the maximum, and in the usage of the electric energy, the ratio of illumination is up to 22%. Accordingly, with a global trend of energy-saving and carbon reduction, the illumination plays a significant role in the current stage.
Currently, main illumination sources are generally incandescent bulbs and fluorescent lamps. Incandescent bulbs have the low cost, but they can not satisfy the global trend of energy-saving and carbon reduction in the current stage due to the disadvantages of high power consumption, low illumination efficiency, and high thermal pollution. Fluorescent lamps are fabricated by glass and have plug openings in the two ends. Accordingly, fluorescent lamps can be connected with the power supply and fixed. Unlike incandescent bulbs, ballasts are required to be installed in fluorescent lamps and co-operates with starters to generate a high transient voltage which ionizes the gas to make fluorescent lamps lighting. The advantages of fluorescent lamps are the low cost and high illumination efficiency. However, fluorescent lamps also have some problems in the usage, such as flickering and pre-heating. The flickering frequency of fluorescent lamps is related to the driving voltage. The flickering of fluorescent lamp is not easy to be sensed by human eyes. However, the flickering may generate fan effect in some environments, which limits and affects the application in the environments. The pre-heating of fluorescent lamp may change the brightness in the initial lighting and after being used for a time period. Due to light emitting diodes (LEDs) having advantages of long lifespan, high illumination efficiency, stable brightness, LEDs become a mainstream product of next generation for lighting and illuminating.
The application of LEDs is fairly extensive, for example, indoor illumination, outdoor illumination, advertisement boards, back light module of electronic products, and so forth. In the foregoing application, the problems of the LEDs, such as high cost and heat dissipation are rapidly improved, and the overall permeability will rapidly increase in the future. With the LEDs gradually replacing current illumination sources, how to suitably drive the LEDs serving as illumination sources and provide suitable protection has now become one of the most important tasks. Accordingly, the LEDs can bring their capability into full play and the safety can also be enhanced in the usage.